Belt-type conveyors are utilized extensively for transferring articles or objects from one station to another. In such conveyors, there is normally provided an endless belt trained around a pair of end rollers, with additional intermediate idler or tensioning rollers also being provided. The upper reach of the belt is normally utilized for supporting the articles being transferred. In some conveyors, normally referred to as horizontal belt conveyors, the upper belt reach extends substantially horizontally and thus merely transfers the objects between two different horizontally spaced stations. Other conveyors, normally referred to as inclined conveyors, have at least a part of the upper belt reach extending upwardly at an angle with respect to the horizontal so as to permit a vertical lifting of the articles as they are transported between two working stations.
In these known conveyors, the drive is normally connected to only one of the end rollers so that the belt is thus under a substantial tension in order to effect operation of the conveyor. Because of the tension in the belt, it is necessary for the conveyor to be provided with complex alignment structure, associated with both the belt and the roller, so as to permit proper tracking of the belt. If the rollers and belts are not properly aligned, then the tension in the belt causes the belts to continually move sidewardly of the rollers so that the side edges of the belt rub against the guide structure, thereby resulting in excessive wear. The tension in the belt thus makes the overall conveyor more complex by requiring costly alignment structure, and additionally makes set-up and operation more difficult in view of the necessity of having this structure precisely adjusted. Since this is difficult to accomplish, undesirable wear of the belt is normally encountered during usual operation of such conveyors.
In addition to the above problems, belt conveyors of the inclined type possess still further structural and operational disadvantages. Particularly, in inclined conveyors wherein the upper belt reach has a portion projecting horizontally and a further portion inclined upwardly, it is necessary to provide guide structure throughout the curve (the junction) between the horizontal and inclined portions) in order to maintain the desired curvature of the upper belt reach. Absent this guide structure, which normally comprises guide rails disposed for engagement with the upper side edges of the belt, the proper curvature of the belt can not be maintained in view of the large tension which exists in the belt. The use of these top guide rails is, however, undesirable in view of the excessive rubbing and wear which they cause on the belt. In addition to the top guide rails, it has also often been necessary to provide an additional control roller at the curve in order to maintain the belt in the desired path, but this control roller greatly restricts the applicability of the conveyor for many uses.
Because of the excessive belt tension required in these known belt conveyors, a problem of bowing of the belt across the width thereof has also been experienced. To overcome this problem, it has been conventional to provide cross rails on the belt so as to strengthen same and prevent bowing. This not only increases the cost and complexity of the belt, but also increases the complexity of driving and controlling the belt.
Accordingly, it is an object of the present invention to provide an improved belt conveyor which overcomes the above-mentioned disadvantages. More specifically, the belt conveyor of this invention includes a drive arrangement which is connected to and simultaneously drives both of the end rollers which support the belt so that the belt is maintained with little, if any, tension therein during operation of the system.
Another object of this invention is to provide an improved belt conveyor, as aforesaid, which minimizes the problem of belt tracking and excessive belt wear, and which also eliminates the need for complex and costly alignment structure due to the belt being maintained in a condition wherein it is substantially free of tension.
Still another object of this invention is the provision of a belt conveyor, as aforesaid, which is particularly desirable for use as an inclined conveyor wherein the belt can be deflected from a horizontal position into an upwardly inclined position without requiring any top guide rails or other top control rollers at or throughout the curve between the horizontal and inclined portions of the belt.
A further object of this invention is an improved belt conveyor, as aforesaid, which is simple to manufacture and assemble, which is of minimum cost and mechanical complexity, which operates in an efficient manner while requiring minimum adjustment and maintenance, which is suitable for use as either a horizontal or inclined conveyor, and which permits the use of either a friction or a toothed drive between the rollers and belt depending upon the magnitude of the transported load and/or the angle of inclination.
In the belt conveyor of this invention, the belt extends between a pair of end rollers which support the upper reach of the belt so that same extends horizontally or, in the alternative, a part of this upper reach is inclined upwardly. The pair of end rollers are simultaneously driven from a common drive source so that the upper belt reach is maintained in a virtually tensionless condition. The upper reach of the belt, when a portion thereof is inclined, is supported on horizontal guide members positioned beneath the upper reach, and the curved portion of the upper reach is supported solely by said guide members. A toothed driving arrangement can be provided between the rollers and the belt to prevent slippage therebetween, which toothed drive arrangement additionally functions as an alignment structure to ensure proper alignment of the belt on the rollers.
Other objects and purposes of this invention will be apparent to persons familiar with structures of this type upon reading the following specification and inspecting the accompanying drawings.